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Based on the coupling algorithm of smoothed particle hydrodynamics and finite element method, numerical simulation of high-velocity water jet impacting heterogeneous concrete containing aggregates according to the real concrete CT slices was conducted to study the damage evolutions and fracture characteristics of concrete with real structure. The damage evolution and fragmentation process of heterogeneous concrete were obtained, and the fracture characteristic was compared with homogeneous concrete. The internal energy change laws and the damage and stress evolutions in homogeneous and heterogeneous concretes at different time were investigated. And the failure mechanisms of water jet crushing heterogeneous concrete were revealed. The results show that the concrete elements mainly suffer multi-stage plastic damage accumulation failure induced by water jet impact due to stress wave effect, pressured water wedge effect, water flow scouring effect, squeezing effect of aggregate, and stress concentrations. The failures of upper and deep concrete elements are mainly caused by compressive shear stress, which is combined with tensile stress. In homogeneous concrete, the bowl-shaped broken pit with smooth sidewall and the symmetrically distributed cracks are formed. In heterogeneous concrete, the aggregate will prolong the damage accumulation process and lead to the formation of the abnormal broken pit with irregular and rough contour. Cracks prefer to propagate at interface between aggregate and mortar, and concrete elements at interfaces will suffer the sudden brittle failure caused by stress concentration when the damage accumulates to a certain extent. Overall, the internal energy in concrete first rapidly and then slowly increases, and there is a poorer absorption efficiency of jet kinetic energy for heterogeneous concrete, in which the internal energy of aggregates and mortar is closely related to the specific impact object of water jet. The research results would lay the theoretical foundation for water jet efficiently crushing concrete. [Display omitted] • Water jet impacting concrete with actual aggregates was simulated and verified. • Damage evolution and fragmentation process were investigated. • Energy changes and damage-stress evolutions were compared. • Failure mechanisms of heterogeneous concrete were revealed. [ABSTRACT FROM AUTHOR]

Numerical simulations were conducted based on SPH-FEM coupling method to investigate the damage evolutions and failure mechanism of rock impacted by a high-velocity water jet under different stress loading conditions. The influences of stress loading magnitudes and stress differences on the rock fracture characteristics, including parameters of broken pit morphology and crack propagation, were obtained. The development of damage and crack inner rock will be inhibited due to stress loadings. The rock failure mechanism in different breakage zones were revealed by exploring the damage and stress evolutions inner rock. The results show that the rock surface elements near jet impact center suffers from the instantaneous brittle failure, which is scarcely affected by stress loadings. The elements inner rock below jet impact and sidewall elements surrounding broken pit are destroyed due to the cumulative plastic damage, and the stress loadings delay the initial damage time and prolong the cumulative damage time. [Display omitted] • Breakage response of rock impacted by water jet under stress loading was studied. • Effects of stress magnitudes and stress differences on macro fracture characteristics were obtained. • Damage and stress evolution laws of rock elements were analyzed. • Failure mechanisms of rock elements in different breakage zones were revealed. [ABSTRACT FROM AUTHOR]